However, the local occurrence of poorly graphitized carbonaceous material in amphibolite-facies rocks supports the idea that graphitization is not simply due to increasing temperature and pressure.

Chromium is primarily added to offset the graphitizing effects of nickel and silicon in types A, B, and C alloys, ranges from 1.4 to 3.5%. Chromium content must be increased with increasing section size.

Chromium is included in these alloys, at levels from 1.4 to 4% to ensure that the irons will solidify with carbides to counteract the graphitizing effect of nickel.